Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 340921
Title Concentration and Solvency Effects on the Pair Interaction between Colloidal Particles in a Solution of Nonadsorbing Polymer
Author(s) Tuinier, R.; Fleer, G.J.
Source Macromolecules 37 (2004)23. - ISSN 0024-9297 - p. 8764 - 8772.
Department(s) Physical Chemistry and Colloid Science
Publication type Refereed Article in a scientific journal
Publication year 2004
Keyword(s) mesoscopic particles - depletion - dispersions - potentials - mixtures - spheres - chains - phase - adsorption - molecules
Abstract Analytical expressions are derived for the polymer excess amount and the grand potential (surface free energy) of flat and spherical surfaces immersed in a solution of nonadsorbing polymer chains in the mean-field approximation. We start from a recent mean-field expression for the depletion thickness which takes into account not only the effect of the chain length N but also that of the polymer concentration b and the solvency . Simple expressions are obtained for the interfacial properties at a colloidal surface, using both the adsorption method and the osmotic route. For a sphere of radius a, the excess amount can be separated into a planar contribution = -b and a curvature correction c = -(2/12)bc2/a, where c is a "curvature thickness" which is close to (but smaller than) . The grand potential has a planar contribution = (2/9)b/ and a curvature part c = (/18)b/a. We test the results against numerical lattice computations, taking care that the boundary conditions in the continuum and lattice models are the same. We find good agreement up to a polymer segment volume fraction of 10%, and even for more concentrated solutions our simple model is reasonable. For spherical geometry we propose a new equation for the segment concentration profile which excellently agrees with numerical lattice computations. The results can be used as a starting point for the pair interaction between colloidal particles in a solution containing nonadsorbing chains, which is discussed in the following paper.
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